Constant torque clutch



marcn 4U, 1843.

O. O. SUNDERLAND CONSTANT TORQUE CLUTCH Filed May 18, 1942 INVENTOR OSWALD QSUNDERLAND I Y A .ORNEY Patented Mar. 20, 1945 I 2,371,855 CONSTANT TORQUE CLUTCH Oswald Sunderland, Fairfield, Conn.

Application May 18, 1942, Serial No. 443,422

6 Claims.

This invention relates to new and useful improvements in clutches and has particular relation to a clutch for delivering a constant torque and which includes means adjustable whereby the maximum torque to be delivered by the clutch may be varied.

The objects and advantages of the invention will become apparent from a consideration of the following detailed description taken in connection with the accompanying drawing wherein satisfactory embodiments of the invention are shown. However, it is to be understood that the invention is not limited to the details disclosed but includes all such variations and modifications as fall within the spirit of the invention and the scope of the appended claims.

In the drawing:

Fig. 1 is a top plan view of the clutch of the invention, the housing thereof being in longitudinal section;

Fig. 2 is a central vertical sectional view through the clutch, including the complete housing, the view being taken as along the plane of the line 2-2 of Fig. 1;

Fig. 3 is a View similar to Fig. 2 but showing a modification; and

Fig. 4 is a transverse sectional view taken as along the plane of the line 4-4 of Fig. 3 but through the complete clutch.

The clutch of the invention is particularly for use in connections where overloads are likely to be placed on a power transmission system. Such overloads, unless absorbed, may result in the breakage of parts, the stalling of a prime mover, or the like. With the clutch of the invention only up to a predetermined torque may be transmitted and an overload being applied to the clutch, eithe suddenly or otherwise, the elements of the clutch are opened without damage to any part of th'e clutch and without damage to any part of a system in which the clutch is incorporated. I

My clutch finds ready application in trucks, tanks and like vehicles as well as in other connections wherein overloads are likely to be suddenly impressed on a mechanical system. The clutch may be associated with the individual drive wheels and tracks of trucks and tanks or may be interposed between an engine and a transmission, or the like. In mechanisms of the kind to use in such devices.

Referring in detail to the drawing and at first more particularly to Figs. 1 and 2 my clutch as shown includes a cylindrical housing 10 including an integral end wall II and a removable end wall l2. Within housing m are complemental clutch elements comprising driving clutch element [3 and driven clutch element l4. Element I3 is associated with a head l5 and the latter includes a reduced diameter integral extension it onto which the element is threaded as at H. A sleeve-like extension l8 projects from the other side of head l5 through a bearing IS in the housing wall l2.

A second head 20 within housing I0 is secured to the end wall I l of the housing and includes an integral reduced diameter extension 2| externally threaded as at 22 and onto which is threaded the clutch element l4. Head 20 is secured to the housing wall by any desired means as, for example, the screws 23. On the free end portions of the extensions l 6 and 2|, respectively, are stops in the form of collars 24 and 25 rigid with the extensions. Attention is here directed to the fact that the extensions are threaded in opposite directions and the purpose of such construction will be set forth.

A heavy coil spring 26 has its respective end portions disposed in notches or recesses 21 and 28 in the head l5 and element l3 while a similar but oppositely coiled spring 29 has its respective end portions disposed in notches 0r recesses 30 and 3| in the head 20 and element M. A driving shaft 32 passes through the head 15 and its extensions l6 and I8 and is keyed to the head to drive the same the keys being shown at 33. The inner end of shaft 32 has bearing in the forward portion of the extension 2| of head 20 and the shaft may be driven in any suitable manner and by any desired means.

At the outer side of housing wall l2 a limiting means or collar 34 is threaded onto the sleevelike extension l8 and a set screw 35 provides means whereby the collar may be locked to the sleeve-like extension against any casual movement relative thereto. A coil spring 36 bears against the head 15 and also against a thrust bearing 31 at the inner side of the wall l2. Spring 36 is constantly tending to move head l5 and its associated parts in the direction of head 20 or in a direction to have the clutch elements l3 and I4 normally engaged.

The outer end portion of the sleeve-like extension IB is provided with a groove 38 receiving pins 39 carried by the arms 40 of a yoke 4|. Such yoke is pivoted at 42 onto a suitable bracket 43 and has integral therewith or rigidly connected thereto a manual or lever 44. Clearly on rocking of this lever 44 in one direction the sleeve I6 and therefore the head I and extension I6 will be drawn in a direction to carry the clutch element I3 away from the element I4. Also on the lever 44 being thereafter released the coil spring 36 will return the mentioned parts to normal positions with the clutch element I3 engaged with the element I4.

When the clutch is not in use the stop 34 is spaced from wall I2 as shown. Head I5 is driven in any suitable manner as by the shaft 32 (it being understood that the shaft is shown merely to illustrate a complete embodiment of the invention). When the head is turned. in a direction tending to wind up the spring 26 and unwind the spring 29, both springs being normally without tension, the head I5 and extension I6 turn relative to element I3 until the spring 26 is tensioned. During such relative turning movement element I3 is threaded back on extension l6 but is kept in full engagement with element I4 since the assembly I3, I6 and I5 is being pressed forward by spring 36.

On spring 26 being sufiiciently tensioned it drives the element I3 with head I5 and thus drives element I4 in a direction tending to uncoil spring 29. Thus element I4 is fed outwardly on its threaded extension 2| into tight engagement with stop 25. Then head 20, extension 2| and element I4 form a solid mass and said head is rotated with the element and drives shaft 45.

The spring 26 is designed to deliver only a predetermined constant maximum torque and should an overload be placed on head [5 the spring 26 will not be rigid enough to transmit such overload but will transmit the predetermined constant torque and will Yield in a direction to further coil. As this occurs the head and its extension I6 turn in the element I3 and due to the screw threaded connection between said element and extension I6 the element is fed back further on the extension in a direction away from the element I4. However, spring 36 feeds the parts forward to keep element I3 in full driving relation with element I4 until stop 34 comes against wall I2 when further threading of element I3 on extension |6 result. in slipping of element I3 on element I4 preventing transmission of the overload while yet delivering the predetermined torque.

Unless element I4, extension 2| and head are being held they will be rotated by element I3 during the initial movements set forth but the driven parts will probably be rotated at a lower speed and as these parts gain momentum spring 26 returns the element |3 and extension I6 back toward normal relationship. On removal of the entire load spring 26 returns such parts to the normal relationship,

When head I5 is driven in the opposite direction, that is in a direction tending to unwind spring 26, the head and its extension I6 initially move relative to element I3 with the result that the latter is fed forward on the extension and jammed against stop 24. Then head I5 and element I3 move as a unit and element I3 drives element I4 in a direction to wind spring 29 and the initial movement of element I4 is to wind such spring and feed the element back along extension 2| until the spring has suflicient tension to drive head 26. As element I4 moved back on extension 2| spring 36 caused element 13 to follow and keep in driving relation with said element I4.

On an overload being applied spring 29 being designed to deliver only a predetermined maximum constant torque is further coiled resulting in further feeding of element I4 in a direction away from element I3 but the spring 36 functions to keep these parts in full driving relation until and unless stop 34 is advanced into engagement with the wall I2. When this last occurs element I4 may lose full driving relation with element I3 and slip on the latter but element I3 is delivering the constant torque and as element I4 and parts driven thereby gain momentum the relation of the parts shifts back to normal as will be understood.

From the foregoing it will be seen that while the head I5 is being driven in one direction the continued application of an overload will result in element I3 being fed in a direction away from full driving relation with element I4 and if the overload is applied while the head I5 is being driven in the opposite direction the element I4 will be fed in a direction away from full driving relation with element I3. However, at all times element I3 is delivering the predetermined constant torque. The elements are not moved out of contact but to such relation that element I3 delivering the constant torque is slipping on element 14 until the overload is removed as by the driven element I4 reaching the speed of the driving element I3.

End wall I2 is threaded into the housing I0 and is fixed against casual movement by a set screw 41. On loosening of this screw and adjusting the wall inwardly or outwardly the relation of the stop 34 to said wall may be varied. In this way the overload points of the clutch may be adjusted. The same result may be obtained by adjusting the stop 34 on the sleeve-like extension. 48 are sockets in wall I2 and are adapted to be engaged by a tool for the purpose of turning such wall in making an adjustment of the latter.

The clutch of Figs. 3 and 4 is somewhat simpler in construction than that of Figs. 1 and 2 but is designed for slipping of its elements only when an overload is applied when driving in one direction. On the clutch of Figs. 3 and 4 being driven in the opposite direction its elements are forced tight against one another and are not released on the application of an overload.

Referring in detail to Figs. 3 and 4 the clutch there shown includes a housing 50 having one integral end wall 5| and an end wall 52 threaded into place and secured there as by a set screw 53. This wall 52 is provided with the recesses or sockets 48 for the purpose above set forth. Within housing 50 is a driven clutch element 54 having a shaft 55 connected thereto or integral therewith and a driving clutch element 56 screwed onto a threaded portion 51 of an extension 58. The outer portion 59 of said extension has bearing in the element 54 and the inner portion of said extension has bearing in a head 60 and therein is provided with or has formed thereon a worm gear 6| meshing with a worm 62 mounted in said head.

Worm 62 is held in place by a screw 63 and meshing with the worm gear 6| holds the extension 58 in fixed relation to the head 66. An opening 64 gives access to the worm whereby the latter may be turned to adjust the extension 58 relative to the head 60 for a purpose to be described. Screws 65 secure head 66 to wall 5| and such head has connected thereto or formed integral therewith a shaft 66 extending through wall and adapted to be rotated by any suitable means.

A heavy coil spring 61 has its respective end portions disposed in sockets 68 and 69 in the driving clutch element 56 and the head 60. With the described construction as the head is driven the extension 58 rotates with it and as the head is driven in one direction the movement is transmitted by spring 6! to clutch element 56 and the latter drives element 54 and shaft 55. This movement of the head is in a direction tending to further coil spring 61 but unless there is an overload the spring is not further coiled but simply delivers the load to element 56.

On an overload being applied the sprin is further coiled and the head and extension move as a unit but relative to the clutch element 56 and thus the latter (owing to the threaded connection of said element with its extension) is fed back in a direction away from element 54 slipping on the latter but continuing to deliver the predetermined constant torque for which spring 61 is set. When the head is driven in the opposite direction or in a direction tending to unwind spring 6! element 56 is fed forward into tight engagement with element 54 and there is no slippage on an overload being applied.

The overload point of the clutch of Figs. 3 and 4 is dependent on the tension of spring 61 and the tension of the latter may be adjusted to set the spring for the delivery of the desired load. This adjustment is accomplished through the manipulation of the worm 62 whereby to cause relative rotation of the extension 58 and the clutch element and the head and casing 50 to further wind up or to partly release the spring 67.

Having thus set forth the nature of my invention, what I claim is:

1. In a clutch, a pair of spaced heads having extensions arranged in opposing relation, complemental clutch elements on said extensions, a coil spring forming a driving connection between each head and the clutch element on its extension, means for turning one of said heads, said extensions having threaded engagement with the respective clutch elements and threaded in onposite directions, and said springs coiled in opposite directions whereby on turning of said head in one direction the spring of said head will yield on overload and its clutch element will be fed in a direction away from the other clutch element and on turning of the said head in the opposite direction the spring of the other head will yield on overload and its clutch element will be fed in a direction away from the clutch element of the first head.

2. The clutch as in claim 1 including spring means normally maintaining one of said heads in position with its clutch element in engagement with the complemental clutch element, and manual means for shifting said head and its clutch element in a direction to carry the latter away from said complemental clutch element.

3. The clutch as in claim 1 including stops on said extensions and limiting movements of the clutch elements toward the ends of their respective extensions whereby on turning of said head in the first direction the clutch element of the other head is threaded forward against its stop and forms a turnable unit with its extension and head and on turning of said head in the opposite direction its clutch element isfed forward against its stop and forms a solid unit with its extension and said head.

4. The clutch as in claim 1 including a housing enclosing said heads and elements, means securing the other of said heads to a wall of said housing, a sleeve-like extension on said head and passing through the other wall of said housing, a shaft passing through said sleeve-like extension and having driving connection with said head, a spring against said head and said other wall of the housing and normally maintaining said head with its clutch element in engagement with the other clutch element, and manual means connected with said sleeve-like extension at the exterior of said housing and operable to shift said head and its clutch element against the action of said spring.

5. The clutch as in claim 1 including means adjustable to vary the overload points of the clutch.

6. The clutch as in claim 1 including spring means operable to urge one clutch element and its associated parts toward the other clutch element as one is shifted in a direction away from the other on its threaded mounting, and a stop limiting such movement of said element and its parts by the spring.

OSWALD O. SUNDERLAND. 

